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EAU 2018: Discovery of a Novel Gene Expression Profile of Renal Papilla Including Randall’s Plaque From Calcium Phosphate Over Calcium Oxalate Stone Formers

Copenhagen, Denmark (UroToday.com) Dr. Taguchi, clinical urologist from the Nagoya City University in Nagoya, Japan, presented his findings of a novel gene expression profile to better understand the prevalence and development of a Randall’s plaque (RP) which eventually leads to calcium oxalate (CaOx) and calcium phosphate (CaP) stone formation. Dr. Taguchi begins his presentation by discussing previous studies that occurred at his center, which determined that renal cell injury, oxidative stress, and sodium/potassium transporters contribute to RP development. He further expanded on this to point out that other studies have indicated the differences of lithogenesis between CaOx and CaP stones from RP. In this current study, Dr. Taguchi hoped to elucidate the lithogenesis of these two stone types by using gene expression profiles of the papilla tissue from each stone forming patient.

The study progressed by using renal papilla biopsy tissues from 23 idiopathis CaOx and 7 CaP stone formers who had previously undergone PCNL and flexible URS. These patients were further divided based on whether the renal papillary mucosa contained an RP or whether it did not contain an RP. Additionally, as a control, 7 renal papillary mucosa biopsies were collected from patients who were not stone formers but were receiving ureteroscopy for screening. To analyze these tissues, microarray analysis was used to compare their gene expression patterns. Also, Ingenuity Pathway Analysis® was carried out to determine causal pathways.

Between the three cohorts of patients, only one patient characteristic was statistically significant which was the level of serum creatinine in the CaP stone formers. Following cluster analysis, gene expression profiles for CaP patients were markedly different from CaOx and control groups. It was shown that RP tissue from CaP stone formers had significantly greater cell movements of granulocytes, neutrophils, or T lymphocytes than the CaOx cohort.

To summarize his results, Dr. Taguchi reiterated how complex and vastly different the gene expression profiles were between the CaP and CaOx stone former cohorts. He explained what he thought was the most important difference, however, which was more pro-inflammatory and immune-active responses led to the RP formation on a CaP stone. Therefore, Dr. Taguchi and his team were successful in determining the gene expression profiles and determining a major difference between these two stone former types.

Speaker: Kazumi Taguchi

Authors: : Taguchi K. , Hamamoto S. , Tanaka Y. , Sugino T. , Unno R. , Ando R. , Okada A. , Kohri K. , Yasui T.

Written by: Zachary Valley, Department of Urology, University of California-Irvine, at the 2018 European Association of Urology Meeting EAU18, 16-20 March, 2018 Copenhagen, Denmark